Add global test setup

Configure chai and SandboxedModule in a central place and add
SandboxedModule globals that are required in Node 12.

services/notifications/test/setup.js

@@ -0,0 +1,21 @@
+const chai = require('chai')
+const SandboxedModule = require('sandboxed-module')
+
+// Chai configuration
+chai.should()
+
+// SandboxedModule configuration
+SandboxedModule.configure({
+  requires: {
+    'logger-sharelatex': {
+      debug() {},
+      log() {},
+      info() {},
+      warn() {},
+      err() {},
+      error() {},
+      fatal() {}
+    }
+  },
+  globals: { Buffer, JSON, console, process }
+})